This description relates to checkpointing a collection of data units.
There are various types of data processing systems in which the ability to recover or restart in response to a failure or other unexpected event is useful. For example, in real-time stream processing or complex event processing systems, it is useful to save system information such as input data and/or state information for computations being performed on the input data. Checkpointing is an example of a way to periodically save system information so that the system is able to recover from a recently saved consistent state. One example of a checkpointing technique for a data processing system that operates on a continuous flow of data is described in U.S. Pat. No. 6,584,581, incorporated herein by reference.